This invention relates generally to a winch, and more specifically pertains to a high capacity hoisting system for use in a helicopter, and which incorporates dual drums, each having its own winch cable, thereby providing a margin of safety even in the event of a mechanical failure in one of the operating drums.
A variety of winch and hoist drive systems particularly for use in conjunction with the helicopter are available in the prior art. The use of the helicopter, over the past two decades, has become significantly important in both its military and commercial applications. Generally, one main advantage that has enhanced the utility of this craft has been its ability to lift significant loads to extraordinary heights, and it does so with the use of various hoisting means that can initially raise the load from the ground, before the helicopter undertakes some movement to the desired location for reimplacement of its carried load.
While the hoist contributing attributes of the helicopter in the manner as previously described has become significantly important in both, as before stated, the military and commercial applications, there are certain deficiencies in the available art type of mechanisms that render the usage of their structured hoists somewhat deficient, and in many instances, even hazardous of application. For example, most of the hoisting means available in the prior art include the use of a single winch having a single cable pay-out, and with the cable release being performed over the length of its supporting drum, which thereby automatically translates into a slight shifting momentum to the load itself, and in many instances even before it is raised off of the ground or other supporting structure. As a result of this, there is a tendency for the load being lifted by the helicopter to immediately begin to sway upon its release of contact with the ground, which can be extremely hazardous to any surrounding workers or property, as can be fully appreciated. In addition, in those particular prior art applications where the single point delivery system has been incorporated, usually the cable is yet unwound from a drum having some width, with the suspended cable passing through some form of a fairlead assembly for guiding its unwinding cable to a single point delivery. But, the use of various forms of guides for attaining this purpose has usually resulted in the exertion of significant stresses upon the delivered cable, frequently giving rise to fleet angle problems that either can cause the cable to undertake some rotation, and thereby passing on such movement to its suspended load, and at the same time effecting such inherent twisting stresses to the cable that the reverse bends imposed upon the cable can lead to its reduced life and rapid fatigue.
Certain of the foregoing problems can be found in the type of winch systems shown in the earlier United States patents to Beurer, et al., U.S. Pat. No. 3,809,334, and in the United States patent to Worden, et al, U.S. Pat. No. 3,024,001.
Another example of a prior art type of hoisting system is shown in the United States patent to Lemont, U.S. Pat. No. 3,870,255, but which prior art system is more concerned with the drive mechanisms incorporated within the hoisting system, rather than the fall-safe operations of the hoists, and its construction, itself, such as shown and presented in the current invention.
It is, therefore, the principal object of this invention to provide a hoisting system for a helicopter or other hovering craft and which incorporates a pair of oppositely rotating drums for use in simultaneously suspending a pair of cables for lifting purposes.
Another object of this invention is the provision of means for eliminating the usual twisting moments or other forms of undesirable stresses that are normally encountered by the cables of the available winch systems utilized in the hoisting art.
A further object of this invention is the application of an equalizing bar that eliminates the need for non-rotating type cables.
Another object of the invention is the operation of a hoist where its cables depart at one location, thereby eliminating any fleet angle problems and the use of complex level wind systems.
A further object of this invention is the provision of structural means for use in partially supporting the hoisting mechanism built into a helicopter, and which effectively dampens and cushions against any of the vibrations normally generated within the type of an operating and hovering airborne craft and preventing their transmission by means of the hoisting cable to its suspended load.
A further object of this invention is the use of a bearing mounted cable holding means that can simultaneously rotate with its supporting drum and also shift axially thereof so as to provide a constant location for the pay-out of each cable associated with this inventive hoist.
Another object of this invention is the provision of vibration dampening means that is incorporated and acts in conjunction with the speed reducer of this hoist so as to provide both control in the velocity of operations of the hoist while cushioning it against shock or other vibrations normally sustained during helicopter hovering.
A further benefit of this invention is the elimination of cable fatigue problems associated with the conventional type capstan winches.
These and other objects will become more apparent to those skilled in the art upon reviewing the summary of this invention, and upon undertaking a study of its preferred embodiment in view of its drawings.